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Gerry Harp

Trained as a quantum mechanic, Gerry was lured to the SETI Institute by the intriguing possibilities of using the multiple antennas of the Allen Telescope Array to generate images of the sky with thousands of beams smaller than any single antenna could produce. Since his arrival in 2000, he has undertaken many studies on beam formation including the Array’s ability to produce “negative” beams – useful for cancelling out, or “rejecting”, signals from such man-made noise makers as telecommunications satellites. Working with the Allen Telescope Array (ATA) team, this capability is now built-in to the Institute's search system.

For Gerry, trying out new ideas on how signals might be encoded is another exciting angle. While most ETI searches, including those at the Institute, look for the simplest kind of radio signals, he and other scientists are working on techniques to capture more general classes of signals: signals that contain a message from our stellar neighbors. While not abandoning the conventional SETI search, Gerry plans to perform additional kinds of searches in parallel for these message-bearing signals using the unique properties of the ATA which allows multiple simultaneous searches.

And while a SETI detection is a dramatic prospect, Gerry points out that the ATA will really push the envelope for radio astronomy too. It’s not just a new instrument for cosmic research; it’s revolutionary. Lately, he has turned to the problem of making images with radio data, and he's very interested in "imaging SETI," which can extract thousands of times as much information from our radio telescope than more conventional SETI processing. This will speed up the SETI search by a similar factor.

Before venturing into astrophysics more than a decade ago, Gerry started his physics career in surface physics and thin film magnetism. He has expertise in semiconductors, magnetic materials, and low dimensional systems. In this part of his career, Gerry learned a great deal about quantum mechanics, diffraction and holography, and his thesis topic was on the development of a new kind of electron holography to obtain 3D pictures of atoms. Now Gerry uses these same methods performing holography and interferometry with the ATA.

Technical Description of work:

Gerry is currently the director of the Center for SETI Research (CSR) at the Institute, and most of his effort is still focused on doing SETI with the Allen Telescope Array. The ATA is a radio interferometer telescope owned by the SETI Institute and co-operated with SRI International. Gerry is joined by several other scientists and engineers in the CSR looking for artificial signals coming from outside our solar system (SETI). The technical side of this work involves automated control of the ATA and ultra-high speed digital signal processing systems to isolate weak signals potentially from outer space, from the sometimes strong human-made signals all around us.

The other half of the research is deciding where to look. Where should we turn our telescopes to give the best chance of success? One answer is to focus on stars where we already know there are exoplanets and especially exoplanets that might support life. For this reason, CSR's main SETI program now focuses on the Kepler field, the same part of the sky observed by the Kepler space telescope.

On the astrophysics side, Gerry is fascinated by quasars which are by far the brightest astronomical objects. Quasars are thought to be enormous black holes at the centers of galaxies that are gradually devouring their host galaxy. The light (and radio waves) from these objects is so strong that they can easily be viewed at a distance of 10 billion light years. Since the universe itself is only 13 billion years old, this means we are looking back more than halfway to the big bang. How could anything be this bright? Sometimes, quasars are seen to generate visible flashes of light with a duration of <15 minutes. For an object so big, these flashes are extremely short, implying a radiating surface about the same as a sphere with orbital radius of Jupiter. How could anything be so bright? Humans do not entirely understand the physics of quasars, which makes them even more interesting.